1) The percentages given are based on the total amount of monochloro products
formed in each reaction.CH 3 CH 2 CH 3 CH 3 CH 2 CH 2 Cl
ClCl (^2) +CH
3 CHCH 3
Propane Propyl chloride Isopropyl chloride
light, 25 oC
(45%) (55%)
CH 3 CCH 3
CH 3
CH 3 CHCH 3
CH 3
CH 3 CHCH 2 Cl
Cl
Cl 2
CH 3
- Isobutane Isobutyl chloride tert-butyl chloride
(63%) (37%)
light, 25 oC
CH 3 CCH 2 CH 3
CH 3
H
ClCH
Cl
Cl
Cl
Cl 2
2 CCH 2 CH 3
CH 3
CH 3 CCH 2 CH 3
CH 3
CH 3 CCHCH 3
CH 3
CH 3 CCH 2 CH 2
CH 3
2-Methylbutane 1-Chloro-2methyllbutane 2-Chloro-2-methylbutane
2-Chloro-3-meyhylbutane
(30%) (22%)
(33%) (15%)
1-Chloro-3-methylbutane
300 oC
- 3° hydrogen atoms of an alkane are most reactive, 2° hydrogen atoms are
next most reactive, and 1° hydrogen atoms are the least reactive. - Breaking a 3° C–H bond requires the least energy, and breaking a 1° C–H
bond requires the most energy. - The step in which the C–H bond is broken determines the location or orientation
of the chlorination ⇒ the Eact for abstracting a 3° hydrogen atom to be the least
and the Eact for abstracting a 1° hydrogen atom to be greatest ⇒ 3° hydrogen
atoms should be most reactive, 2° hydrogen atoms should be the next most
reactive, and 1° hydrogen atoms should be the the least reactive. - The difference in the rates with which 1°, 2°, and 3° hydrogen atoms are